Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/30/1996
Publication Date: N/A
Citation: Interpretive Summary: Continuous monocropping of a sole species (such as corn or soybean), although widely used as a cropping system in the United States and Europe, leads to poor soil health, increased disease and insect pests, high inputs of fertilizer, and ultimately reductions in yield. Strip intercropping of multiple species (such as corn or canola adjacent to soybean) may alleviate emany of the negative effects of continuous sole crops. To evaluate the hypothesis that strip intercropping is more profitable than monocropping, we grew alternating strips 20 to 25 feet wide (18 rows) of canola and soybean and compared the economic yield of the strip intercrop systems versus monocultures of canola and soybean. Total seed oil, crude protein, and farm profitability were enhanced by strip intercropping. In addition, land use efficiency was improved in the strip intercrop system as compared to the sole crop. These results show that strip intercropping of canola with soybean has the potential to improve profitability and reduce fertilizer application for oilseed production as compared to a sole crop farming system.
Technical Abstract: Increased world demand for high quality edible oil requires agronomic practices for increased yields with minimal environmental impact. We hypothesized that strip intercrops of canola (Brassica napus L. cv. 'Global') and soybean [Glycine max (L.) Merr cv. 'Chippewa'] would increase seed dry matter, oil, and protein yield, and would result in higher net economic gain compared to sole crops. Canola was grown in 4.8 m wide strips (25 cm row spacing) adjacent to 4.8 m strips of later planted soybean in two separate experiments at Rosemount and St. Paul, MN, in 1991 and 1992. Zero or 134 kg N/ha was applied at planting. Seed dry matter, oil, and crude protein (CP) concentrations were determined for individual rows and Land Equivalency Ratio (LER) calculated. Canola border row yields were 223% to 589% those of sole crop rows. Soybean border row yields were similar to those of sole crop rows under low soil N levels but were 50 to 65% of the sole crop yields under high soil N. Projected LER values range from 1.02 to 1.65, but were significantly greater than 1.0 for strip widths of 1 to 4m without N and up to 6m with fertilizer N. Seed oil and crude protein concentration varied slightly among row positions, but total oil and crude protein yields were enhanced in the strip intercrop. Canola soybean strip intercrops generated higher net returns than the average of the sole crops. These results suggest that oilseed yields and profitability in canola soybean intercrops can be improved up to 6m strip width, compared with growing 2 crops separately. Strip intercropping canola and soybean has the potential to reduce fertilizer applications and enhance land use efficiency for oilseed production compared with sole crops.